python theading.Timer: how to pass argument to the callback?

Question

My code:

    import threading  def hello(arg, kargs):     print arg  t = threading.Timer(2, hello, "bb") t.start()  while 1:     pass 

The print out put is just:

b 

How can I pass a argument to the callback? What does the kargs mean?

Answer 1

Timer takes an array of arguments and a dict of keyword arguments, so you need to pass an array:

import threading  def hello(arg):     print arg  t = threading.Timer(2, hello, ["bb"]) t.start()  while 1:     pass 

You're seeing "b" because you're not giving it an array, so it treats "bb" an an iterable; it's essentially as if you gave it ["b", "b"].

kwargs is for keyword arguments, eg:

t = threading.Timer(2, hello, ["bb"], {arg: 1}) 

See http://docs.python.org/release/1.5.1p1/tut/keywordArgs.html for information about keyword arguments.